I had a social media experience recently that shook me, and the more I reflect, the more worried I become -- as a citizen, a teacher, and a dad.

I was surprised that a friend who believes in kindness, empathy and respectful discourse posted a mean-spirited meme about a political controversy. It was a smug, gratuitous dig that didn't advance the debate.

We all sometimes act in ways that contradict our beliefs. My own actions frequently fall short of my ideals. The meme itself wasn't the issue, though, so much as the conversation that followed. When someone expressed surprise at the meme's tone, my friend acknowledged it was juvenile but said an ideological opponent had been particularly annoying that day. My friend shared the meme in response, knowing it was a cheap shot - in fact, choosing it because it was a cheap shot - that would upset the foe. My friend intentionally discarded those values of kindness, respect and reasoned discourse, to get under someone's skin.

Sadly, we needn't look far for examples of people abandoning core values for the sake of political fights, or because they decide someone else deserves censure, shame or anger. We have become so polarized politically that we see things through an increasingly partisan, ideological or tribal lens. As a dad and a teacher, I worry about the message this sends our children. We rightly lament the vicious way some teens treat each other on social media, but I wonder if we have helped create that environment.

If I drop a plastic straw in the gutter, it will become part of that massive plastic island polluting the ocean. Yes, it's only one straw, but a lot of people are dropping those straws. Similarly, if I contribute to a snarky, disrespectful climate by tweeting a mean-spirited jab or sharing a snarky meme, can I be surprised that teens absorb, and then mimic, those actions? Children, including teens, learn by consistency and modeling. No matter what we say, they mirror what we do. If they see adults being mean online, they will do the same.

We may preach respect, but our behavior, both online and in person, is teaching children that it's acceptable to be rude as long as it's funny, or directed at people we dislike. It has become permissible - even encouraged - to take cheap shots, reduce complex problems to memes and turn human beings into caricatures. It's even fine to inflict emotional distress, as long as the recipient "deserves" it - in our opinion.

That's not righteousness; it's self-righteousness, a fancy-dress version of self-indulgence. If children learn their morality from self-indulgent adults, we will have done them a disservice. We will also have created a world, both real and digital, that I don't think most of us would like to inhabit, much less raise our children in.

And it goes beyond social media. Acting in a way that matches our values, morals and basic norms of decency is important because humans are prone to mistakes when passions overtake judgment. Consistent values prevent us from doing whatever we feel like, which protects us and others, and they increase our chances of living peacefully. History provides many chilling examples of how quickly people can become monsters when the principle of human dignity is removed, both destroying their own humanity and stripping it from others.

If I judge someone unworthy of courtesy and respect, if I use my own opinion or feelings as an excuse to ignore basic decency, I may damage another person. And I will almost certainly damage myself. At a minimum, I will stunt growth, and cut myself off from relationships and experiences that might expand and enrich my life. That is not something I want for my children.

Speaking and behaving in a way that matches my values may seem small, but so is that straw. It may not change the world, but it can help prevent things from getting worse. Striving for moral consistency requires me to suppress impulses in favor of something greater, and that imposes a sort of moral humility that helps protect against hubris and prejudice. Those things seem worth giving up the chance to take a cheap shot at someone I disagree with.

We all want our children to inherit a safe world with clean air and water. We take action to help make that happen. I've been trying to avoid one-use plastic products lately, for example. Wouldn't creating a more respectful environment be worth a similar effort, especially online? If I'm willing to change my consumption habits, I should be able to show some sort of moral consistency in my social media interactions.

Yes, many politicians and other public figures lack integrity, restraint and respect. It's tempting to stoop to their level. But we shouldn't let their lack of moral consistency corrode our own, so that we leave a terrible example for our kids.

The answer is simple and difficult. It requires practicing what we preach, and modeling what we want others to do, consistently, without exceptions for ourselves or those we find ideologically sympathetic.

Of course, we will all fall short. We may even fail spectacularly. But hopefully, our children will at least see that we are trying, and that it's worth an effort. The horrifying alternative is to leave to our children a world where no one even tries.

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Bell is a teacher, writer and director from Nashville. The author of seven novels, he blogs and writes a newsletter with reflections about parenting adolescents. He's on Twitter @bradenbellcom.